I'm thinking the rope was floating in the water and got caught in the prop and wrapped around the rudder at speed. As the prop spun and tightened the rope, it torqued the strut and rudder enough to crack the fiberglass and gel coat, and eventually to remove the prop blades before the load stopped the engine.

But that's pure fantasy; I'll be interested in hearing the real story.

/frank

Maybe you mean pure speculation? Pure fantasy is in the swimsuit thread.....